The present invention relates to a method of administering wake times in an interconnected assembly of several control devices and a time base control device. The present invention also relates to an interconnected assembly of several control devices and a time base control device for a motor vehicle, wherein each control device and the time base control device include a memory unit for receiving wake times.
Control devices are utilized in an increasing degree in modern motor vehicles and are interconnected with one another for example through a so-called CAN bus. The control devices operate for performing different functions, for example for controlling the stage heating. Many of the utilized control devices, for example also the stage heating control device, require a time base which supplies the time and when necessary the date to perform corresponding time-dependent tasks. Each control device is joined through its own time base, and a synchronization of all time bases is performed in a network. Because of the complexity and hardware expense for the plurality of time bases available in a network, it has been further proposed to operate a time base centrally in the network. This central time base has the advantage that the control-relevant time data, hereinafter referred to wake times, are administered, and the actual time for all control devices in the net are made ready.
Thus, from the prior art it is for example known to administer all wake times of all control devices available in the net from a time base control device (hereinbelow identified as time control device). For example the stage heating control device which participates in turning on and turning off of the time control device, after reaching a predetermined time point sends a message to the stage heating control device and induces it for releasing the corresponding action. During a selection of control devices in a network, this procedure leads however to a substantial expense for administering and storing the wake times.
An improvement of the procedure is achieved when the time device administers only the actual wake time of each control device. Here each control device must transmit only the next wake time to the time control device. Upon reaching the wake time, the control device is "awaken", to perform its action and to communicate to the time control device the next wake time (as long as it is available). As a result the time control device for each control device to be awakened must be supplied only with one time. The disadvantage of this solution however is that the time control device for each control device available in the network must administer a memory place, so that with each new incoming control device the memory requirement increases and the memory administering expenses correspondingly increase.